PROJECT SUMMARY/ABSTRACT The X-ray unit is a fundamental tool in the clinical setting providing high diagnostic yield for low cost. Its use is over-looked in preclinical studies due to the resolution necessary to visualize anatomical structures relevant to DXA the smaller research species. We requests funds for the purchase of a Faxitron Ultrafocus to serve as an initial low cost surveillance tool for monitoring the general health status/phenotyping of our rodent species prior to considering more costly and time intensive 3-D imaging. The Faxitron UltrafocusDXA is a self-contained, cabinet style X-ray system capable of resolving both anatomical/physiological features down to 8 microns. The unit is designed to provide small animal in vivo imaging with inclusion of an anesthesia port and viewing window for monitoring depth of anesthesia. The fine detailed images provide qualitative and quantitative information over a diverse range of experimental models including visualization of tumors with bony metastases, quantifying elongation of bone and healing of bone fractures, and visualization of soft tissue structures (vasculature, organs) via the aide of contrast media. Monitoring of disease progression or therapeutic effectiveness is readily achievable at the whole animal level. The Faxitron is also outfitted with a Dual-energy X-ray Absorptiometry (DXA) component allowing quantitative measurements of bone mass, bone mineral density, % fat and % lean tissue maps. The DXA scanning component provides quantitative measurements of bone loss or gain, and this feature along with the high resolution images allows phenotyping of genetically altered mice. Resulting images are suitable for publication and are of a greater quality than that produced by the Piximus unit (current gold standard). As a testament to its versatility, minor users include the UW Department of Agronomy for seed analysis, Wisconsin Veterinary Diagnostic Lab for necropsy needs (imaging of zoo and wildlife species) and the UW Comparative Orthopaedic Research Lab for histological purposes. Overall, this unit will serve as an excellent cost-effective, user-friendly resource enabling investigators in multiple departments and disciplines to acquire initial surveillance images of animal and plant specimens, and to examine the complexity of various structures in a convenient, accessible format. Such technology will accelerate, enhance, and expand their current research and level of inquiry. It will provide new opportunities for collaboration and external research funding.